This is a very easy question, no need to ask for help at all. Especially
when you said it's urgent, why didn't you try it yourself? It only
took me less than 3 minutes to find the following information.
The following document says for B-2 visitors, you need to file form I-539
to extend your stay: http://www.uscis.gov/USCIS/Resources/C1en.pdf
And, form I-539 is right here: http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e
3f6d1a/?vgnextoid=94d12c1a6855d010VgnVCM10000048f3d6a1RCRD
And, you can file it online: http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e
3f6d1a/?
vgnextoid=ac3d8424f8304110VgnVCM1000004718190aRCRD&vgnextchannel=9059d9808
bcbd010VgnVCM100000d1f1d6a1RCRD
All I did was one Google query: "visa extension".
